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help / color / mirror / Atom feedFrom: Andrei Lepikhov <[email protected]>
To: David Rowley <[email protected]>
Cc: PostgreSQL-development <[email protected]>
Cc: Alena Rybakina <[email protected]>
Subject: Re: Memoize ANTI and SEMI JOIN inner
Date: Mon, 31 Mar 2025 09:45:18 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAApHDvpd-qnqgpCmLnb-T8yNjtFUX4J65D7+pOEz67dRs1+Ldg@mail.gmail.com>
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On 3/31/25 05:33, David Rowley wrote:
> I can't say definitively that we won't find a reason in the future
> that we should set inner_unique for SEMI/ANTI joins, so I don't follow
> the need for the Assert.
>
> Maybe you're seeing something that I'm not. What do you think will
> break if both flags are true?
I considered targeting PG 19 and July Comitfest for this feature, but
currently, I don't see any further development needed here. What are
your thoughts, David? Does it make sense to commit this to PG 18?
I have no reason to rush the process, but this feature seems beneficial
for practice. When the internal structure is a bushy join tree,
producing even a single tuple can be costly. SQL Server's Spool node
addresses this issue, and people sometimes experience confusion
detecting degradation during migration with specific queries.
--
regards, Andrei Lepikhov
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